Semiconductor device and method of manufacture

ABSTRACT

A semiconductor device and method for providing an enhanced removal of heat from a semiconductor die within an integrated fan out package on package configuration is presented. In an embodiment a metal layer is formed on a backside of the semiconductor die, and the semiconductor die along and through vias are encapsulated. Portions of the metal layer are exposed and a thermal die is connected to remove heat from the semiconductor die.

PRIORITY DATA

The present application is a continuation application of U.S.application Ser. No. 14/555,405, filed Nov. 26, 2014, which is herebyincorporated by reference in its entirety.

BACKGROUND

The semiconductor industry has experienced rapid growth due tocontinuous improvements in the integration density of a variety ofelectronic components (e.g., transistors, diodes, resistors, capacitors,etc.). For the most part, this improvement in integration density hascome from repeated reductions in minimum feature size (e.g., shrinkingthe semiconductor process node towards the sub-20 nm node), which allowsmore components to be integrated into a given area. As the demand forminiaturization, higher speed and greater bandwidth, as well as lowerpower consumption and latency has grown recently, there has grown a needfor smaller and more creative packaging techniques of semiconductordies.

As semiconductor technologies further advance, stacked and bondedsemiconductor devices have emerged as an effective alternative tofurther reduce the physical size of a semiconductor device. In a stackedsemiconductor device, active circuits such as logic, memory, processorcircuits and the like are fabricated at least partially on separatesubstrates and then physically and electrically bonded together in orderto form a functional device. Such bonding processes utilizesophisticated techniques, and improvements are desired.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates formation of through vias, in accordance with someembodiments.

FIGS. 2A-2B illustrate embodiments of a semiconductor device with ametal layer, in accordance with some embodiments.

FIG. 3 illustrates a placement of the semiconductor device between thethrough vias, in accordance with some embodiments.

FIG. 4 illustrates an encapsulation of the semiconductor device andthrough vias, in accordance with some embodiments.

FIG. 5 illustrates formation of a redistribution layer and externalconnections, in accordance with some embodiments.

FIG. 6 illustrates a debonding of a carrier wafer, in accordance withsome embodiments.

FIGS. 7A-7B illustrate an exposure of the metal layer, in accordancewith some embodiments.

FIG. 8 illustrates a singulation of the semiconductor device, inaccordance with some embodiments.

FIG. 9 illustrates a bonding of a thermal die, in accordance with someembodiments.

FIG. 10 illustrates another embodiment in which a seed layer is utilizedon the back side of the semiconductor device, in accordance with someembodiments.

FIG. 11 illustrates a placement of the semiconductor device between thevias, in accordance with some embodiments.

FIG. 12 illustrates an encapsulation and formation of a redistributionlayer, in accordance with some embodiments.

FIG. 13 illustrates an exposure of the seed layer in accordance withsome embodiments.

FIG. 14 illustrates a singulation of the semiconductor device, inaccordance with some embodiments.

FIG. 15 illustrates a bonding of the thermal die, in accordance withsome embodiments.

FIGS. 16A-16B illustrate embodiments of a joint, in accordance with someembodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

With reference now to FIG. 1, there is shown a carrier substrate 101with an adhesive layer 103, a polymer layer 105, and a first seed layer107 over the carrier substrate 101. The carrier substrate 101 comprises,for example, silicon based materials, such as glass or silicon oxide, orother materials, such as aluminum oxide, combinations of any of thesematerials, or the like. The carrier substrate 101 is planar in order toaccommodate an attachment of semiconductor devices such as a firstsemiconductor device 201 and a second semiconductor device 301 (notillustrated in FIG. 1 but illustrated and discussed below with respectto FIGS. 2A-3).

The adhesive layer 103 is placed on the carrier substrate 101 in orderto assist in the adherence of overlying structures (e.g., the polymerlayer 105). In an embodiment the adhesive layer 103 may comprise anultra-violet glue, which loses its adhesive properties when exposed toultra-violet light. However, other types of adhesives, such as pressuresensitive adhesives, radiation curable adhesives, epoxies, combinationsof these, or the like, may also be used. The adhesive layer 103 may beplaced onto the carrier substrate 101 in a semi-liquid or gel form,which is readily deformable under pressure.

The polymer layer 105 is placed over the adhesive layer 103 and isutilized in order to provide protection to, e.g., the firstsemiconductor device 201 and the second semiconductor device 301 oncethe first semiconductor device 201 and the second semiconductor device301 have been attached. In an embodiment the polymer layer 105 may bepolybenzoxazole (PBO), although any suitable material, such as polyimideor a polyimide derivative, Solder Resistance (SR), or Ajinomoto build-upfilm (ABF) may alternatively be utilized. The polymer layer 105 may beplaced using, e.g., a spin-coating process to a thickness of betweenabout 2 μm and about 15 μm, such as about 5 μm, although any suitablemethod and thickness may alternatively be used.

The first seed layer 107 is formed over the polymer layer 105. In anembodiment the first seed layer 107 is a thin layer of a conductivematerial that aids in the formation of a thicker layer during subsequentprocessing steps. The first seed layer 107 may comprise a layer oftitanium about 1,000 Å thick followed by a layer of copper about 5,000 Åthick. The first seed layer 107 may be created using processes such assputtering, evaporation, or PECVD processes, depending upon the desiredmaterials. The first seed layer 107 may be formed to have a thickness ofbetween about 0.3 μm and about 1 μm, such as about 0.5 μm.

FIG. 1 also illustrates a placement and patterning of a photoresist 109over the first seed layer 107. In an embodiment the photoresist 109 maybe placed on the first seed layer 107 using, e.g., a spin coatingtechnique to a height of between about 50 μm and about 250 μm, such asabout 120 μm. Once in place, the photoresist 109 may then be patternedby exposing the photoresist 109 to a patterned energy source (e.g., apatterned light source) so as to induce a chemical reaction, therebyinducing a physical change in those portions of the photoresist 109exposed to the patterned light source. A developer is then applied tothe exposed photoresist 109 to take advantage of the physical changesand selectively remove either the exposed portion of the photoresist 109or the unexposed portion of the photoresist 109, depending upon thedesired pattern.

In an embodiment the pattern formed into the photoresist 109 is apattern for vias 111. The vias 111 are formed in such a placement as tobe located on different sides of subsequently attached devices such asthe first semiconductor device 201 and the second semiconductor device301. However, any suitable arrangement for the pattern of vias 111, suchas by being located such that the first semiconductor device 201 and thesecond semiconductor device are placed on opposing sides of the vias111, may alternatively be utilized.

In an embodiment the vias 111 are formed within the photoresist 109. Inan embodiment the vias 111 comprise one or more conductive materials,such as copper, tungsten, other conductive metals, or the like, and maybe formed, for example, by electroplating, electroless plating, or thelike. In an embodiment, an electroplating process is used wherein thefirst seed layer 107 and the photoresist 109 are submerged or immersedin an electroplating solution. The first seed layer 107 surface iselectrically connected to the negative side of an external DC powersupply such that the first seed layer 107 functions as the cathode inthe electroplating process. A solid conductive anode, such as a copperanode, is also immersed in the solution and is attached to the positiveside of the power supply. The atoms from the anode are dissolved intothe solution, from which the cathode, e.g., the first seed layer 107,acquires the dissolved atoms, thereby plating the exposed conductiveareas of the first seed layer 107 within the opening of the photoresist109.

Once the vias 111 have been formed using the photoresist 109 and thefirst seed layer 107, the photoresist 109 may be removed using asuitable removal process (not illustrated in FIG. 1 but seen in FIG. 3below). In an embodiment, a plasma ashing process may be used to removethe photoresist 109, whereby the temperature of the photoresist 109 maybe increased until the photoresist 109 experiences a thermaldecomposition and may be removed. However, any other suitable process,such as a wet strip, may alternatively be utilized. The removal of thephotoresist 109 may expose the underlying portions of the first seedlayer 107.

Once exposed a removal of the exposed portions of the first seed layer107 may be performed (not illustrated in FIG. 1 but seen in FIG. 3below). In an embodiment the exposed portions of the first seed layer107 (e.g., those portions that are not covered by the vias 111) may beremoved by, for example, a wet or dry etching process. For example, in adry etching process reactants may be directed towards the first seedlayer 107 using the vias 111 as masks. In another embodiment, etchantsmay be sprayed or otherwise put into contact with the first seed layer107 in order to remove the exposed portions of the first seed layer 107.After the exposed portion of the first seed layer 107 has been etchedaway, a portion of the polymer layer 105 is exposed between the vias111.

FIG. 2A illustrates a first semiconductor device 201 that will beattached to the polymer layer 105 within the vias 111 (not illustratedin FIG. 2 but illustrated and described below with respect to FIG. 3).In an embodiment the first semiconductor device 201 comprises a firstsubstrate 203, first active devices (not individually illustrated),first metallization layers 205, first contact pads 207, a firstpassivation layer 211, and first external connectors 209. The firstsubstrate 203 may comprise bulk silicon, doped or undoped, or an activelayer of a silicon-on-insulator (SOI) substrate. Generally, an SOIsubstrate comprises a layer of a semiconductor material such as silicon,germanium, silicon germanium, SOI, silicon germanium on insulator(SGOI), or combinations thereof. Other substrates that may be usedinclude multi-layered substrates, gradient substrates, or hybridorientation substrates.

The first active devices comprise a wide variety of active devices andpassive devices such as capacitors, resistors, inductors and the likethat may be used to generate the desired structural and functionalrequirements of the design for the first semiconductor device 201. Thefirst active devices may be formed using any suitable methods eitherwithin or else on the first substrate 203.

The first metallization layers 205 are formed over the first substrate203 and the first active devices and are designed to connect the variousactive devices to form functional circuitry. In an embodiment the firstmetallization layers 205 are formed of alternating layers of dielectricand conductive material and may be formed through any suitable process(such as deposition, damascene, dual damascene, etc.). In an embodimentthere may be four layers of metallization separated from the firstsubstrate 203 by at least one interlayer dielectric layer (ILD), but theprecise number of first metallization layers 205 is dependent upon thedesign of the first semiconductor device 201.

The first contact pads 207 may be formed over and in electrical contactwith the first metallization layers 205. The first contact pads 207 maycomprise aluminum, but other materials, such as copper, mayalternatively be used. The first contact pads 207 may be formed using adeposition process, such as sputtering, to form a layer of material (notshown) and portions of the layer of material may then be removed througha suitable process (such as photolithographic masking and etching) toform the first contact pads 207. However, any other suitable process maybe utilized to form the first contact pads 207. The first contact padsmay be formed to have a thickness of between about 0.5 μm and about 4μm, such as about 1.45 μm.

The first passivation layer 211 may be formed on the first substrate 203over the first metallization layers 205 and the first contact pads 207.The first passivation layer 211 may be made of one or more suitabledielectric materials such as silicon oxide, silicon nitride, low-kdielectrics such as carbon doped oxides, extremely low-k dielectricssuch as porous carbon doped silicon dioxide, combinations of these, orthe like. The first passivation layer 211 may be formed through aprocess such as chemical vapor deposition (CVD), although any suitableprocess may be utilized, and may have a thickness between about 0.5 μmand about 5 μm, such as about 9.25 KÅ.

The first external connectors 209 may be formed to provide conductiveregions for contact between the first contact pads 207 and, e.g., aredistribution layer 501 (not illustrated in FIG. 2 but illustrated anddescribed below with respect to FIG. 5). In an embodiment the firstexternal connectors 209 may be conductive pillars and may be formed byinitially forming a photoresist (not shown) over the first passivationlayer 211 to a thickness between about 5 μm to about 20 μm, such asabout 10 μm. The photoresist may be patterned to expose portions of thefirst passivation layers through which the conductive pillars willextend. Once patterned, the photoresist may then be used as a mask toremove the desired portions of the first passivation layer 211, therebyexposing those portions of the underlying first contact pads 207 towhich the first external connectors 209 will make contact.

The first external connectors 209 may be formed within the openings ofboth the first passivation layer 211 and the photoresist. The firstexternal connectors 209 may be formed from a conductive material such ascopper, although other conductive materials such as nickel, gold, ormetal alloy, combinations of these, or the like may also be used.Additionally, the first external connectors 209 may be formed using aprocess such as electroplating, by which an electric current is runthrough the conductive portions of the first contact pads 207 to whichthe first external connectors 209 are desired to be formed, and thefirst contact pads 207 are immersed in a solution. The solution and theelectric current deposit, e.g., copper, within the openings in order tofill and/or overfill the openings of the photoresist and the firstpassivation layer 211, thereby forming the first external connectors209. Excess conductive material and photoresist outside of the openingsof the first passivation layer 211 may then be removed using, forexample, an ashing process, a chemical mechanical polish (CMP) process,combinations of these, or the like.

However, as one of ordinary skill in the art will recognize, the abovedescribed process to form the first external connectors 209 is merelyone such description, and is not meant to limit the embodiments to thisexact process. Rather, the described process is intended to be merelyillustrative, as any suitable process for forming the first externalconnectors 209 may alternatively be utilized. All suitable processes arefully intended to be included within the scope of the presentembodiments.

On an opposite side of the first substrate 203 than the firstmetallization layers 205, a first metal layer 213 may be placed in orderto assist with removing heat from the first semiconductor device 201. Inan embodiment the first metal layer 213 may be placed by initiallyapplying a first glue layer 214 onto the first substrate 203. The firstglue layer 214 may be an epoxy, although any suitable adhesive may alsobe utilized. The first glue layer 214 may be applied to a thickness ofbetween about 0.5 μm and about 20 μm.

Once the first glue layer 214 has been applied to the first substrate203, the first metal layer 213 may be applied. In an embodiment thefirst metal layer 213 may be a conductive material such as copper,although other suitable materials include Ti, TiN, and Ta. In anembodiment the first metal layer 213 may be a copper foil that has afirst thickness of between about 3 μm and about 150 μm. The copper foilmay be applied by contacting the copper foil to the first glue layer214.

Adjacent to the first metal layer 213 a die attach film (DAF) 217 may beformed in order to assist in the attachment of the first semiconductordevice 201 to the polymer layer 105. In an embodiment the die attachfilm 217 is an epoxy resin, a phenol resin, acrylic rubber, silicafiller, or a combination thereof, and is applied using a laminationtechnique. However, any other suitable alternative material and methodof formation may alternatively be utilized.

FIG. 2B illustrates another embodiment of the first semiconductor device201 which utilizes the first metal layer 213. In this embodiment, thefirst metal layer 213 may be applied without the first glue layer 214.Optionally in this embodiment a first barrier layer 219 may be appliedprior to the formation of the first metal layer 213 in order to preventdiffusion of the material of the first metal layer 213 into theunderlying first substrate 203. In an embodiment the first barrier layer219 may comprise a barrier material such as titanium, titanium nitride,combinations of these, or the like, and may be formed using a processsuch as chemical vapor deposition (CVD), physical vapor deposition(PVD), atomic layer deposition (ALD), or the like. The first barrierlayer 219 may be formed to have a thickness of between about 0.1 μm andabout 20 μm, such as about 0.5 μm.

Once the first barrier layer 219 has been formed, the first metal layer213 may be formed over the first barrier layer 219. In this embodimentthe first metal layer 213 may be formed using a deposition process suchas physical vapor deposition (PVD), although any suitable deposition orplacement process may alternatively be utilized. In an embodiment thefirst metal layer 213 may be formed to have a thickness of between about0.02 μm and about 0.5 μm, such as about 0.3 μm, and the first metallayer 213 and the first barrier layer 219 (collectively) may have athickness of between about 0.3 μm and about 15 μm.

Optionally, once the first metal layer 213 has been formed on the firstbarrier layer 219, a second barrier layer 221 may be formed over thefirst metal layer 213 in order to prevent the material of the firstmetal layer 213 (e.g. copper) from diffusing into adjacent structures.In an embodiment the second barrier layer 221 may be similar to thefirst barrier layer 219 (e.g., titanium or titanium nitride formed usingCVD, PVD, or ALD), although it may alternatively be different.

In this embodiment, once either the first metal layer 213 or the secondbarrier layer 221 has been formed, the die attach film 217 may beapplied in order to assist with the adhesion of the first semiconductordevice 201 to the polymer layer 105. In an embodiment the die attachfilm 217 is as described above with respect to FIG. 2A.

FIG. 3 illustrates a placement of the first semiconductor device 201onto the polymer layer 105 along with a placement of a secondsemiconductor device 301. In an embodiment the second semiconductordevice 301 may comprise a second substrate 303, second active devices(not individually illustrated), second metallization layers 305, secondcontact pads 307, a second passivation layer 311, and second externalconnectors 309. In an embodiment the second substrate 303, the secondactive devices, the second metallization layers 305, the second contactpads 307, the second passivation layer 311, and the second externalconnectors 309 may be similar to the first substrate 203, the firstactive devices, the first metallization layers 205, the first contactpads 207, the first passivation layer 211, and the first externalconnectors 209, although they may also be different.

Additionally, the second semiconductor device 301 may also have a secondmetal layer 313 formed along a side of the second substrate 303. In anembodiment the second metal layer 313 may be formed along with a secondglue layer (not separately illustrated in FIG. 3) or along with a thirdbarrier layer and fourth barrier layer (also not separately illustratedin FIG. 3). In an embodiment the second metal layer 313, the second gluelayer, the third barrier layer, and the fourth barrier layer may besimilar to the first metal layer 213, the first glue layer 214, thefirst barrier layer 219, and the second barrier layer 221 describedabove with respect to FIGS. 2A-2B, although they may be different.

In an embodiment the first semiconductor device 201 and the secondsemiconductor device 301 may be placed onto the polymer layer 105 using,e.g., a pick and place process. However, any other alternative method ofplacing the first semiconductor device 201 and the second semiconductordevice 301.

FIG. 4 illustrates an encapsulation of the vias 111, the firstsemiconductor device 201 and the second semiconductor device 301. Theencapsulation may be performed in a molding device (not individuallyillustrated in FIG. 4), which may comprise a top molding portion and abottom molding portion separable from the top molding portion. When thetop molding portion is lowered to be adjacent to the bottom moldingportion, a molding cavity may be formed for the carrier substrate 101,the vias 111, the first semiconductor device 201, and the secondsemiconductor device 301.

During the encapsulation process the top molding portion may be placedadjacent to the bottom molding portion, thereby enclosing the carriersubstrate 101, the vias 111, the first semiconductor device 201, and thesecond semiconductor device 301 within the molding cavity. Onceenclosed, the top molding portion and the bottom molding portion mayform an airtight seal in order to control the influx and outflux ofgasses from the molding cavity. Once sealed, an encapsulant 401 may beplaced within the molding cavity. The encapsulant 401 may be a moldingcompound resin such as polyimide, PPS, PEEK, PES, a heat resistantcrystal resin, combinations of these, or the like. The encapsulant 401may be placed within the molding cavity prior to the alignment of thetop molding portion and the bottom molding portion, or else may beinjected into the molding cavity through an injection port.

Once the encapsulant 401 has been placed into the molding cavity suchthat the encapsulant 401 encapsulates the carrier substrate 101, thevias 111, the first semiconductor device 201, and the secondsemiconductor device 301, the encapsulant 401 may be cured in order toharden the encapsulant 401 for optimum protection. While the exactcuring process is dependent at least in part on the particular materialchosen for the encapsulant 401, in an embodiment in which moldingcompound is chosen as the encapsulant 401, the curing could occurthrough a process such as heating the encapsulant 401 to between about100° C. and about 130° C., such as about 125° C. for about 60 sec toabout 3000 sec, such as about 600 sec. Additionally, initiators and/orcatalysts may be included within the encapsulant 401 to better controlthe curing process.

However, as one having ordinary skill in the art will recognize, thecuring process described above is merely an exemplary process and is notmeant to limit the current embodiments. Other curing processes, such asirradiation or even allowing the encapsulant 401 to harden at ambienttemperature, may alternatively be used. Any suitable curing process maybe used, and all such processes are fully intended to be included withinthe scope of the embodiments discussed herein.

FIG. 4 also illustrates a thinning of the encapsulant 401 in order toexpose the vias 111, the first semiconductor device 201, and the secondsemiconductor device 301 for further processing. The thinning may beperformed, e.g., using a mechanical grinding or chemical mechanicalpolishing (CMP) process whereby chemical etchants and abrasives areutilized to react and grind away the encapsulant 401, the firstsemiconductor device 201 and the second semiconductor device 301 untilthe vias 111, the first external connectors 209 (on the firstsemiconductor device 201), and the second external connectors 309 (onthe second semiconductor device 301) have been exposed. As such, thefirst semiconductor device 201, the second semiconductor device 301, andthe vias 111 may have a planar surface that is also planar with theencapsulant 401.

However, while the CMP process described above is presented as oneillustrative embodiment, it is not intended to be limiting to theembodiments. Any other suitable removal process may alternatively beused to thin the encapsulant 401, the first semiconductor device 201,and the second semiconductor device 301 and expose the vias 111. Forexample, a series of chemical etches may be utilized. This process andany other suitable process may alternatively be utilized to thin theencapsulant 401, the first semiconductor device 201, and the secondsemiconductor device 301, and all such processes are fully intended tobe included within the scope of the embodiments.

Optionally, after the encapsulant 401 has been thinned, the vias 111 andthe first external connectors 209 may be recessed within the encapsulant401. In an embodiment the vias 111 and the first external connectors 209may be recessed using, e.g., an etching process that utilizes an etchantthat is selective to the material of the vias 111 and the first externalconnectors 209 (e.g., copper). The vias 111 and the first externalconnectors 209 may be recessed to a depth of between about 20 μm andabout 300 μm, such as about 180 μm.

FIG. 5 illustrates a formation of a redistribution layer (RDL) 501 inorder to interconnect the first semiconductor device 201, the secondsemiconductor device 301, the vias 111 and third external connectors505. In an embodiment the RDL 501 may be formed by initially forming aseed layer (not shown) of a titanium copper alloy through a suitableformation process such as CVD or sputtering. A photoresist (also notshown) may then be formed to cover the seed layer, and the photoresistmay then be patterned to expose those portions of the seed layer thatare located where the RDL 501 is desired to be located.

Once the photoresist has been formed and patterned, a conductivematerial, such as copper, may be formed on the seed layer through adeposition process such as plating. The conductive material may beformed to have a thickness of between about 1 μm and about 10 μm, suchas about 5 μm. However, while the material and methods discussed aresuitable to form the conductive material, these materials are merelyexemplary. Any other suitable materials, such as AlCu or Au, and anyother suitable processes of formation, such as CVD or PVD, mayalternatively be used to form the RDL 501.

Once the conductive material has been formed, the photoresist may beremoved through a suitable removal process such as ashing. Additionally,after the removal of the photoresist, those portions of the seed layerthat were covered by the photoresist may be removed through, forexample, a suitable etch process using the conductive material as amask.

FIG. 5 also illustrates a formation of a third passivation layer 503over the RDL 501 in order to provide protection and isolation for theRDL 501 and the other underlying structures. In an embodiment the thirdpassivation layer 503 may be polybenzoxazole (PBO), although anysuitable material, such as polyimide or a polyimide derivative, mayalternatively be utilized. The third passivation layer 503 may be placedusing, e.g., a spin-coating process to a thickness of between about 5 μmand about 25 μm, such as about 7 μm, although any suitable method andthickness may alternatively be used.

Additionally, while FIG. 5 only illustrates a single RDL 501 and asingle third passivation layer 503, this is done for clarity and is notintended to limit the embodiments. Rather, the above processes to formthe single RDL 501 and the single third passivation layer 503 may berepeated one or more times to form a plurality of RDLs 501 and thirdpassivation layers 503 as desired. Any suitable number of RDLs 501 maybe utilized.

FIG. 5 further illustrates a formation of the third external connectors505 to make electrical contact with the RDL 501. In an embodiment afterthe third passivation layer 503 has been formed, an opening may be madethrough the third passivation layer 503 by removing portions of thethird passivation layer 503 to expose at least a portion of theunderlying RDL 501. The opening allows for contact between the RDL 501and the third external connectors 505. The opening may be formed using asuitable photolithographic mask and etching process, although anysuitable process to expose portions of the RDL 501 may be used.

In an embodiment the third external connectors 505 may be a ball gridarray and may be placed on the RDL 501 through the third passivationlayer 503 and may comprise a eutectic material such as solder, althoughany suitable materials may alternatively be used. In an embodiment inwhich the third external connectors 505 are solder balls, the thirdexternal connectors 505 may be formed using a ball drop method to placethe third external connectors 505 onto underbump metallizations (UBMs),such as a direct ball drop process. Alternatively, the solder balls maybe formed by initially forming a layer of tin through any suitablemethod such as evaporation, electroplating, printing, solder transfer,and then performing a reflow is preferably performed in order to shapethe material into the desired bump shape. Once the third externalconnectors 505 have been formed, a test may be performed to ensure thatthe structure is suitable for further processing.

FIG. 6 illustrates a debonding of the carrier substrate 101 from thefirst semiconductor device 201 and the second semiconductor device 301.In an embodiment the third external connectors 505 and, hence, thestructure including the first semiconductor device 201 and the secondsemiconductor device 301, may be attached to a ring structure 601. Thering structure 601 may be a metal ring intended to provide support andstability for the structure during and after the debonding process. Inan embodiment the third external connectors 505, the first semiconductordevice 201, and the second semiconductor device 301 are attached to thering structure using, e.g., a ultraviolet tape 603, although any othersuitable adhesive or attachment may alternatively be used.

Once the third external connectors 505 and, hence, the structureincluding the first semiconductor device 201 and the secondsemiconductor device 301 are attached to the ring structure 601, thecarrier substrate 101 may be debonded from the structure including thefirst semiconductor device 201 and the second semiconductor device 301using, e.g., a thermal process to alter the adhesive properties of theadhesive layer 103. In a particular embodiment an energy source such asan ultraviolet (UV) laser, a carbon dioxide (CO₂) laser, or an infrared(IR) laser, is utilized to irradiate and heat the adhesive layer 103until the adhesive layer 103 loses at least some of its adhesiveproperties. Once performed, the carrier substrate 101 and the adhesivelayer 103 may be physically separated and removed from the structurecomprising the third external connectors 505, the first semiconductordevice 201, and the second semiconductor device 301.

FIG. 7A illustrates an optional placement of a backside protection layer701 over the polymer layer 105. In an embodiment the backside protectionlayer 701 may be a protective material such as a Solder Resistance (SR),Lamination Compound (LC), or Ajinomoto build-up film (ABF). In anembodiment the backside protection layer 701 may be applied using alamination technique to a thickness of between about 10 μm and about 80μm, such as about 25 μm.

FIG. 7A also illustrates that, once the backside protection layer 701has been placed, the backside protection layer 701 and the polymer layer105 may be patterned in order to expose the vias 111 and desiredportions of the first metal layer 213 and the second metal layer 313. Inan embodiment the backside protection layer 701 and the polymer layer105 may be patterned using, e.g., a laser drilling method, by which alaser is directed towards those portions of the polymer layer 105 whichare desired to be removed in order to expose the underlying vias 111,the first metal layer 213, and the second metal layer 313. During thelaser drilling process the drill energy may be in a range from 0.1 mJ toabout 30 mJ, and a drill angle of about 0 degree (perpendicular to thebackside protection layer 701) to about 85 degrees to normal of thebackside protection layer 701. In an embodiment the patterning may beformed to form first openings 703 over the vias 111 to have a firstwidth of between about 100 μm and about 300 μm, such as about 200 μm,and also to form second openings 707 over the first semiconductor device201 to have a second width of between about 10 μm and about 300 μm, suchas about 150 μm.

In another embodiment, the backside protection layer 701 and the polymerlayer 105 may be patterned by initially applying a photoresist (notindividually illustrated in FIG. 7A) to the backside protection layer701 and then exposing the photoresist to a patterned energy source(e.g., a patterned light source) so as to induce a chemical reaction,thereby inducing a physical change in those portions of the photoresistexposed to the patterned light source. A developer is then applied tothe exposed photoresist to take advantage of the physical changes andselectively remove either the exposed portion of the photoresist or theunexposed portion of the photoresist, depending upon the desiredpattern, and the underlying exposed portion of the backside protectionlayer 701 and the polymer layer 105 are removed with, e.g., a dry etchprocess. However, any other suitable method for patterning the backsideprotection layer 701 and the polymer layer 105 may be utilized.

Optionally, a cleaning process may be utilized after the laser drillprocess in order to remove any residual material left behind by thelaser drill process. In an embodiment the cleaning process may be aplasma clean process which may also remove a portion of the exposedsurfaces of the backside protection layer 701 and the polymer layer 105.In an embodiment, the plasma clean process is performed using an oxygenplasma, or the like, in an inert atmosphere such a nitrogen, argon, orthe like.

FIG. 7B illustrates a close-up view of one of the second openings 707formed over the first semiconductor device 201 as illustrated by thedashed line labeled 705 in FIG. 7A. As can be seen, the first substrate203, the first metal layer 213 (along with either the first glue layer214 or the first barrier layer 219), the DAF 217, the polymer layer 105and the backside protection layer 701 are stacked, and the secondopening 707 extends through the backside protection layer 701, thepolymer layer 105 and the DAF 217, but stops on the first metal layer213, thereby exposing the first metal layer 213 on the backside of thefirst substrate 203.

Additionally, the second opening 707 has a funnel shape. In anembodiment the second opening 707 has a first width W₁ of between about20 μm and about 300 μm, such as about 100 μm, adjacent to the firstmetal layer 213. Additionally, the second opening 707 has a second widthW₂ of between about 50 μm and about 320 μm, such as about 120 μm, at thetop of the second opening 707. However, any suitable dimensions may beutilized.

By exposing portions of the first metal layer 213 along a backside ofthe first substrate 203, a thermal path may be formed in connection withthe first semiconductor device 201 through the DAF 217, the polymerlayer 105 and the backside protection layer 701 without the need foranother redistribution layer and its associated passivation layer andbond pad simply to remove heat from the first semiconductor device 201.As such, the overall process may be simplified by avoiding the processesassociated with a redistribution layer and bond pads. This allows for amore efficient process to provide a thermal path to remove heatgenerated by the first semiconductor device 201.

FIG. 8 illustrates a singulation of the structure to form a firstpackage 801. In an embodiment the singulation may be performed by usinga saw blade (not shown) to slice through the encapsulant 401 and thepolymer layer 105 between the vias 111, thereby separating one sectionfrom another to form the first package 801 with the first semiconductordevice 201. However, as one of ordinary skill in the art will recognize,utilizing a saw blade to singulate the first package 801 is merely oneillustrative embodiment and is not intended to be limiting. Alternativemethods for singulating the first package 801, such as utilizing one ormore etches to separate the first package 801, may alternatively beutilized. These methods and any other suitable methods may alternativelybe utilized to singulate the first package 801.

FIG. 8 additionally illustrates a placement of a thermally conductiveprotective layer 803 within the first openings 703 and the secondopening 707 over the first semiconductor device 201 in order to protectthe now exposed first metal layer 213 and vias 111. In an embodiment thethermally conductive protective layer 803 may comprise a thermallyconductive material such as solder paste or an oxygen solder protection(OSP), although any suitable material may alternatively be utilized. Inan embodiment the thermally conductive protective layer 803 may beapplied using a stencil, although any suitable method of application mayalternatively be utilized.

FIG. 9 illustrates a placement of a thermal die 900 in thermalconnection with the first metal layer 213 through the thermallyconductive protective layer 803. In an embodiment the thermal die 900comprises thermally conductive material that receives heat from thefirst semiconductor device 201 through, e.g., third contact pads 909,and transmits the heat away from the first semiconductor device 201. Inan embodiment the thermal die 900 may be passive (with only passivetransfer of thermal energy) or may comprise an active transfer systemwhich circulates a cooling medium such as water through the thermal die900 in order to actively move heat away from the first semiconductordevice 201.

Additionally, while the thermal die 900 may comprise materials andstructure solely designed for the purpose of removing heat, embodimentsare not intended to be limited as such. Rather, in other embodiments thethermal die 900 may comprise active devices (such as transistors) andpassive devices (such as resistors and capacitors) which may work toprovide a desired functionality along with the desired removal of heat.Any suitable combination of structures may be utilized with the thermaldie 900 in order to remove heat from the first semiconductor device 201.

To bond the thermal die 900 to the first semiconductor device 201,fourth external connections 910 may be formed on the third contact pads909. In an embodiment the fourth external connections 910 may be contactbumps such as a ball grid array, microbumps, or controlled collapse chipconnection (C4) bumps and may comprise a material such as tin, or othersuitable materials, such as silver or copper. In an embodiment in whichthe fourth external connections 910 are tin solder bumps, the fourthexternal connections 910 may be formed by initially forming a layer oftin through any suitable method such as evaporation, electroplating,printing, solder transfer, ball placement, etc, to a thickness of, e.g.,about 100 μm. Once a layer of tin has been formed on the structure, areflow is performed in order to shape the material into the desired bumpshape.

Once the fourth external connections 910 have been formed, the fourthexternal connections 910 are aligned with and placed into physicalcontact with the thermally conductive protective layer 803 over thefirst metal layer 213, and a bonding is performed. For example, in anembodiment in which the fourth external connections 910 are solderbumps, the bonding process may comprise a reflow process whereby thetemperature of the fourth external connections 910 is raised to a pointwhere the fourth external connections 910 will liquefy and flow, therebybonding the thermal die 900 to the thermally conductive protective layer803 once the fourth external connections 910 resolidifies.

FIG. 9 also illustrates that once the thermal die 900 has been placed, asecond package 902 may be bonded to the vias 111. The second package 902may comprise a third substrate 903, a third semiconductor device 905, afourth semiconductor device 907 (bonded to the third semiconductordevice 905), third contact pads 909, a second encapsulant 911, and fifthexternal connections 913. In an embodiment the third substrate 903 maybe, e.g., a packaging substrate comprising internal interconnects (e.g.,through substrate vias 915) to electrically connect the thirdsemiconductor device 905 to the vias 111.

Alternatively, the third substrate 903 may be an interposer used as anintermediate substrate to connect the third semiconductor device 905 tothe vias 111. In this embodiment the third substrate 903 may be, e.g., asilicon substrate, doped or undoped, or an active layer of asilicon-on-insulator (SOI) substrate. However, the third substrate 903may alternatively be a glass substrate, a ceramic substrate, a polymersubstrate, or any other substrate that may provide a suitable protectionand/or interconnection functionality. These and any other suitablematerials may alternatively be used for the third substrate 903.

The third semiconductor device 905 may be a semiconductor devicedesigned for an intended purpose such as being a logic die, a centralprocessing unit (CPU) die, a memory die (e.g., a DRAM die), combinationsof these, or the like. In an embodiment the third semiconductor device905 comprises integrated circuit devices, such as transistors,capacitors, inductors, resistors, first metallization layers (notshown), and the like, therein, as desired for a particularfunctionality. In an embodiment the third semiconductor device 905 isdesigned and manufactured to work in conjunction with or concurrentlywith the first semiconductor device 201.

The fourth semiconductor device 907 may be similar to the thirdsemiconductor device 905. For example, the fourth semiconductor device907 may be a semiconductor device designed for an intended purpose(e.g., a DRAM die) and comprising integrated circuit devices for adesired functionality. In an embodiment the fourth semiconductor device907 is designed to work in conjunction with or concurrently with thefirst semiconductor device 201 and/or the third semiconductor device905.

The fourth semiconductor device 907 may be bonded to the thirdsemiconductor device 905. In an embodiment the fourth semiconductordevice 907 is only physically bonded with the third semiconductor device905, such as by using an adhesive. In this embodiment the fourthsemiconductor device 907 and the third semiconductor device 905 may beelectrically connected to the third substrate 903 using, e.g., wirebonds 917, although any suitable electrical bonding may be alternativelybe utilized.

Alternatively, the fourth semiconductor device 907 may be bonded to thethird semiconductor device 905 both physically and electrically. In thisembodiment the fourth semiconductor device 907 may comprise thirdexternal connections (not separately illustrated in FIG. 9) that connectwith fourth external connections (also not separately illustrated inFIG. 9) on the third semiconductor device 905 in order to interconnectthe fourth semiconductor device 907 with the third semiconductor device905.

The third contact pads 909 may be formed on the third substrate 903 toform electrical connections between the third semiconductor device 905and, e.g., the fifth external connections 913. In an embodiment thethird contact pads 909 may be formed over and in electrical contact withelectrical routing (such as through substrate vias 915) within the thirdsubstrate 903. The third contact pads 909 may comprise aluminum, butother materials, such as copper, may alternatively be used. The thirdcontact pads 909 may be formed using a deposition process, such assputtering, to form a layer of material (not shown) and portions of thelayer of material may then be removed through a suitable process (suchas photolithographic masking and etching) to form the third contact pads909. However, any other suitable process may be utilized to form thethird contact pads 909. The third contact pads 909 may be formed to havea thickness of between about 0.5 μm and about 4 μm, such as about 1.45μm.

The second encapsulant 911 may be used to encapsulate and protect thethird semiconductor device 905, the fourth semiconductor device 907, andthe third substrate 903. In an embodiment the second encapsulant 911 maybe a molding compound and may be placed using a molding device (notillustrated in FIG. 9). For example, the third substrate 903, the thirdsemiconductor device 905, and the fourth semiconductor device 907 may beplaced within a cavity of the molding device, and the cavity may behermetically sealed. The second encapsulant 911 may be placed within thecavity either before the cavity is hermetically sealed or else may beinjected into the cavity through an injection port. In an embodiment thesecond encapsulant 911 may be a molding compound resin such aspolyimide, PPS, PEEK, PES, a heat resistant crystal resin, combinationsof these, or the like.

Once the second encapsulant 911 has been placed into the cavity suchthat the second encapsulant 911 encapsulates the region around the thirdsubstrate 903, the third semiconductor device 905, and the fourthsemiconductor device 907, the second encapsulant 911 may be cured inorder to harden the second encapsulant 911 for optimum protection. Whilethe exact curing process is dependent at least in part on the particularmaterial chosen for the second encapsulant 911, in an embodiment inwhich molding compound is chosen as the second encapsulant 911, thecuring could occur through a process such as heating the secondencapsulant 911 to between about 100° C. and about 130° C., such asabout 125° C. for about 60 sec to about 3000 sec, such as about 600 sec.Additionally, initiators and/or catalysts may be included within thesecond encapsulant 911 to better control the curing process.

However, as one having ordinary skill in the art will recognize, thecuring process described above is merely an exemplary process and is notmeant to limit the current embodiments. Other curing processes, such asirradiation or even allowing the second encapsulant 911 to harden atambient temperature, may alternatively be used. Any suitable curingprocess may be used, and all such processes are fully intended to beincluded within the scope of the embodiments discussed herein.

In an embodiment the fifth external connections 913 may be formed toprovide an external connection between the third substrate 903 and,e.g., the vias 111. The fifth external connections 913 may be contactbumps such as a ball grid array, microbumps, or controlled collapse chipconnection (C4) bumps and may comprise a material such as tin, or othersuitable materials, such as silver or copper. In an embodiment in whichthe fifth external connections 913 are tin solder bumps, the fifthexternal connections 913 may be formed by initially forming a layer oftin through any suitable method such as evaporation, electroplating,printing, solder transfer, ball placement, etc, to a thickness of, e.g.,about 100 μm. Once a layer of tin has been formed on the structure, areflow is performed in order to shape the material into the desired bumpshape.

Once the fifth external connections 913 have been formed, the fifthexternal connections 913 are aligned with and placed into physicalcontact with the thermally conductive protective layer 803 over the vias111, and a bonding is performed. For example, in an embodiment in whichthe fifth external connections 913 are solder bumps, the bonding processmay comprise a reflow process whereby the temperature of the fifthexternal connections 913 is raised to a point where the fifth externalconnections 913 will liquefy and flow, thereby bonding the secondpackage 902 to the thermally conductive protective layer 803 once thefifth external connections 913 resolidifies.

By forming the first metal layer 213 along a backside of the firstsemiconductor device 201, and then forming an opening through thebackside layers to bond a thermal die to the first metal layer 213, athermal pathway may be formed away from the first semiconductor device201. As such, heat may be quickly and efficiently removed from the firstsemiconductor device 201 without the complexity and cost of formingredistribution layers, passivation layers associated with theredistribution layers, and contact pads on the backside of the firstsemiconductor device 201 for the sole sake of removing heat. As such, asimpler and more cost efficient product may be manufactured.

FIG. 10 illustrates another embodiment in which the first semiconductordevice 201 is utilized. In this embodiment the first semiconductordevice 201 may still comprise the first substrate 203, the first activedevices (not illustrated in FIG. 9), the first metallization layers 205,the first contact pads 207, the first passivation layer 211 and thefirst external connectors 209.

In this embodiment, however, a dual seed layer, e.g., a second seedlayer 1001 and a third seed layer 1003 is formed over the backside ofthe first substrate 203. In an embodiment the second seed layer 1001 maycomprise a thermally conductive material such as titanium, copper,tantalum, titanium nitride, nickel, combinations of these, or the like.In an embodiment the second seed layer 1001 may be formed using adeposition process such as CVD, PVD, or ALD, although any suitablemethod of formation or placement may alternatively be utilized. Thesecond seed layer 1001 may be formed to a thickness of between about 0 Åand about 2000 Å.

The third seed layer 1003 may also be a thermally conductive materialsuch as titanium, copper, tantalum, titanium nitride, nickel,combinations of these, or the like, and may be the same material or adifferent material than the second seed layer 1001. In an embodiment thethird seed layer may be formed using CVD, PVD, or ALD, although anysuitable deposition or placement process may alternatively be utilized,and may be formed to a thickness of between about 500 Å to about 10,000Å. In a particular embodiment the second seed layer 1001 may be titaniumwith a thickness of about 500 Å and the third seed layer 1003 may becopper with a thickness of about 3,000 Å.

Once the second seed layer 1001 and the third seed layer 1003 have beenformed or placed on the first substrate 203, the DAF 21 may be placedover the third seed layer 1003. In an embodiment the DAF 217 may bematerials as described above with respect to FIG. 2. However, anysuitable material may be used to attach the first semiconductor device201 to the polymer layer 105.

FIG. 11 illustrates a placement of the first semiconductor device 201and the second semiconductor device 301 (which may also have a dual seedlayer) onto the polymer layer 105. In an embodiment the polymer layer105 is located over the carrier substrate 101 and the adhesive layer103, and the vias 111 are also located on the polymer layer 105 asdescribed above with respect to FIG. 1. The placement may be performedby a pick and place routine, with the DAF 217 adhering the firstsemiconductor device 201 and the second semiconductor device 301 to thepolymer layer 105.

FIG. 12 illustrates the encapsulation of the first semiconductor device201 and the second semiconductor device 301 with the encapsulant 401. Inan embodiment the encapsulation may be performed as described above withrespect to FIG. 4. For example, the first semiconductor device 201 andthe second semiconductor device 301 are placed into a molding chamber,the encapsulant 401 is injected into the molding chamber, and theencapsulant 401 is then cured. However, any suitable encapsulatingprocess or method may alternatively be utilized.

FIG. 12 also illustrates a thinning of the encapsulant 401 and aformation of the RDL 501, the third passivation layer 503, and the thirdexternal connectors 505. In an embodiment the thinning of theencapsulant 401, the formation of the RDL 501, the third passivationlayer 503, and the third external connectors 505 may be performed asdescribed above with respect to FIGS. 4-5. However, any suitable methodsand materials may alternatively be utilized.

FIG. 13 illustrates an attachment of the first semiconductor device 201and the second semiconductor device 301 to the ring structure 601 and adebonding of the carrier substrate 101 from the first semiconductordevice 201 and the second semiconductor device 301. In an embodiment thefirst semiconductor device 201 and the second semiconductor device 301may be attached to the ring structure 601 and the carrier substrate 101removed as described above with respect to FIG. 6, although any suitablemethod of attaching and removing may alternatively be utilized.

FIG. 13 additionally illustrates formation of third openings 1301 andfourth openings 1303 through the polymer layer 105 without the backsideprotection layer 701. In an embodiment the third openings 1301 and thefourth openings 1303 may be formed using, e.g., a laser drilling method,by which a laser is directed towards those portions of the polymer layer105 which are desired to be removed in order to expose the underlyingvias 111 and portions of the third seed layer 1003. In an embodiment thepatterning may be formed to form the third openings 1301 over the vias111 to have a first width of between about 100 μm and about 300 μm, suchas about 200 μm, and also to form fourth openings 1303 over the firstsemiconductor device 201 to have a second width of between about 15 μmand about 30 μm, such as about 20 μm.

FIG. 14 illustrates a singulation of the first semiconductor device 201from the second semiconductor device 301 to form the first package 801.In an embodiment the first semiconductor device 201 may be singulatedfrom the second semiconductor device 301 as described above with respectto FIG. 8. For example, a saw blade may be utilized to singulate thefirst semiconductor device 201 from the second semiconductor device 301.However, any suitable alternative method may alternatively be utilized.

Optionally at this point, the thermally conductive protective layer 803may be applied within the third openings 1301 and the fourth openings1303. In an embodiment the thermally conductive protective layer 803 maybe applied as described above with respect to FIG. 8. However, anysuitable method may alternatively be utilized.

FIG. 15 illustrates that, once the thermally conductive protective layer803 has been applied, the thermal die 900 and the second package 902 maybe bonded to the first semiconductor device 201 and the vias 111,respectively. In an embodiment the thermal die 900 and the secondpackage 902 may be bonded as described above with respect to FIG. 9. Forexample, the thermal die 900 may be aligned with the fourth openings1303 through the polymer layer 105. Similarly, the second package 902may be aligned with the third openings 1301 through the polymer layer105. Once aligned, a reflow process may be performed in order to bondthe thermal die 900 and the third semiconductor device 905 to the firstpackage 801. However, any suitable method of bonding the thermal die 900and the third semiconductor device 905 may alternatively be utilized.

Optionally, after the thermal die 900 has been bonded, an underfillmaterial 1501 may be dispensed between the thermal die 900 and the firstpackage 801. In an embodiment the underfill material 1501 is aprotective material used to cushion and support the thermal die 900 andthe first package 801 from operational and environmental degradation,such as stresses caused by the generation of heat during operation. Theunderfill material 1501 may be injected or otherwise formed in the spacebetween the thermal die 900 and the first package 801 and may, forexample, comprise a liquid epoxy that is dispensed between the thermaldie 900 and the first package 801, and then cured to harden.

FIG. 16A illustrates a close up view of the joint between the third seedlayer 1003 and the thermally conductive protective layer 803, along withthe fifth external connections 913, in the embodiment illustrated inFIG. 15. In an embodiment the bonded fifth external connections913/thermally conductive protective layer 803 along the joint after thebonding reflow has a first diameter D₁ and the fifth externalconnections 913 over the polymer layer 105 after the bonding has asecond diameter D₂ that is greater than the first diameter D₁. In anembodiment the first diameter D₁ may be between about 20 μm and about150 μm, such as about 100 μm, while the second diameter D₂ may bebetween about 50 μm and about 200 μm, such as about 120 μm. To achievethe structure of FIG. 16A, the critical dimension of the opening throughthe DAF 217 is less than the size of the ball, and the ball size may bebetween about 200 μm and about 400 μm, and an underbump metallizationmay be between about 0.03 μm and about 0.5 μm.

FIG. 16B illustrates another embodiment in which the joint along thesecond seed layer 1003 has a third diameter D₃ that is larger than afourth diameter D₄ of the fifth external connections 913 over thepolymer layer 105. In an embodiment the third diameter D₃ may be betweenabout 100 μm and about 300 μm, such as about 250 μm, while the fourthdiameter D₄ may be between about 50 μm and about 150 μm, such as about120 μm. To achieve the structure of FIG. 16B, the critical dimension ofthe opening through the DAF 217 is less than the size of the ball, andthe ball size may be between about 20 μm and about 200 μm, and anunderbump metallization may be between about 0.03 μm and about 0.5 μm.

By forming the joint as described above, a larger surface area for heattransfer out of the first semiconductor device 201 may be achieved. Witha larger surface area, a larger amount of heat may be more easilyremoved from the first semiconductor device 201 and removed from theoverall device. This leads to a more efficient operation of the firstsemiconductor device 201 and less heat induced failures duringoperation.

In accordance with an embodiment, a semiconductor device comprising afirst semiconductor substrate with first external connections located ona first side of the first semiconductor substrate is provided. A firstplurality of through vias extend through an encapsulant, wherein theencapsulant separates the first semiconductor substrate from the firstplurality of through vias, and a metal layer covers a second side of thefirst semiconductor substrate opposite the first side, wherein the metallayer does not extend over the first plurality of through vias.

In accordance with another embodiment, a semiconductor device comprisinga first semiconductor substrate with a first side and a second sideopposite the second side is provided. First electrical contacts areunder the first side and a metal layer extends over the second side. Afirst through via has a first height greater than a distance from thefirst electrical contact to the metal layer. An encapsulant extendsbetween the first through via and the first semiconductor substrate. Afirst reflowable material is in physical contact with the metal layer. Apolymer layer is over the metal layer and at least partially over aportion of the first reflowable material, and a second reflowablematerial in physical contact with the first reflowable material andextending away from the first semiconductor substrate further than thepolymer layer.

In accordance with yet another embodiment, a method of manufacturing asemiconductor device comprising placing a metal layer on a first side ofa first semiconductor substrate, wherein the first semiconductorsubstrate has active devices located on a second side opposite the firstside is provided. The first semiconductor substrate is placed next to athrough via and the first semiconductor substrate, the metal layer, andthe through via are encapsulated. The encapsulant is thinned to exposethe through via and the metal layer is exposed through a polymer layer.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A device comprising: a first semiconductorsubstrate having a first side and an opposing second side; a first viaextending through an encapsulant, wherein the encapsulant separates thefirst semiconductor substrate from the first via; a metal layer disposedover the second side of the first semiconductor substrate; a die attachfilm disposed on the metal layer; a polymer layer disposed on the dieattach film; a protection layer disposed on the polymer layer; and athermally conductive protective feature extending through the protectionlayer, the polymer layer, the die attach film such that the thermallyconductive protective feature physically contacts the metal layer,wherein the thermally conductive protective feature has a first portionhaving a first width a second portion having a second width that isdifferent than the first width.
 2. The device of claim 1, furthercomprising a seed layer disposed on the polymer layer, and wherein thefirst via physically contacts the seed layer.
 3. The device of claim 1,wherein the thermally conductive protective feature physically contactsthe protection layer, the polymer layer, and the die attach film.
 4. Thedevice of claim 1, wherein the first semiconductor substrate hasopposing sidewalls such that the first and second sides of the firstsemiconductor substrate extend between the opposing sidewalls, andwherein the via has a sidewall surface facing one of the opposingsidewalls of the first semiconductor substrate.
 5. The device of claim1, further comprising: a thermal die bonded to the thermally conductiveprotective feature; and a second semiconductor substrate disposed overthe first semiconductor substrate.
 6. The device of claim 1, furthercomprising a redistribution layer disposed over the first side of thefirst semiconductor substrate, and wherein the first via physicallycontacts the redistribution layer.
 7. The device of claim 6, furthercomprising a passivation layer disposed over the redistribution layer,and wherein the passivation layer physically contacts the encapsulant.8. A device comprising: a metal layer disposed over a firstsemiconductor substrate; a first reflowable material in physical contactwith the metal layer; a die attach film disposed over the metal layerand at least partially over a portion of the first reflowable material;a polymer layer disposed over the die attach film and at least partiallyover the portion of the first reflowable material; and a secondreflowable material in physical contact with the first reflowablematerial and in physical contact with the polymer layer and the dieattach film, the second reflowable material extending away from thefirst semiconductor substrate further than the polymer layer, the secondreflowable material being formed of a different material than the dieattach film.
 9. The device of claim 8, further comprising another metallayer disposed over the first semiconductor substrate in between themetal layer and the first semiconductor substrate.
 10. The device ofclaim 9, wherein the another metal layer physically contacts the firstsemiconductor substrate and the metal layer.
 11. The device of claim 8,further comprising an encapsulant material disposed along a sidewall ofthe first semiconductor substrate, a sidewall of the metal layer, and asidewall of the die attach film such that the encapsulant materialphysically contacts the sidewall of the first semiconductor substrate,the sidewall of the metal layer, and the sidewall of the die attachfilm.
 12. The device of claim 11, further comprising a redistributionlayer disposed over a first side of the first semiconductor substrate,the metal layer being disposed over an opposing second sidesemiconductor substrate, and wherein the encapsulant material extendscontinuously from the polymer layer to the redistribution layer.
 13. Thedevice of claim 8, further comprising: a thermal die bonded to thesecond reflowable material; and a second semiconductor substratedisposed over the thermal die.
 14. The device of claim 8, wherein thefirst reflowable material has a greater width than the second reflowablematerial.
 15. A method comprising: forming a polymer layer over a firstsemiconductor substrate; forming a through via over the polymer layer;placing a semiconductor device on the polymer layer, the semiconductordevice including: a second semiconductor substrate; a metal layer; and adie attach film; forming a trench through the polymer layer and the dieattach film to expose a portion of the metal layer; and forming athermally conductive feature in the trench, wherein the thermallyconductive feature extends through the polymer layer and the die attachfilm to the metal layer, wherein the thermally conductive feature has afirst portion having a first width a second portion having a secondwidth that is different than the first width.
 16. The method of claim15, wherein forming the through via over the polymer layer occurs priorto placing the semiconductor device on the polymer layer.
 17. The methodof claim 15, after placing the semiconductor device on the polymerlayer, encapsulating the semiconductor device and the through via in anencapsulating material.
 18. The method of claim 17, further comprisingremoving a portion of the encapsulating material to expose the throughvia.
 19. The method of claim 15, further comprising forming a protectionlayer on the polymer layer, and wherein forming the trench through thepolymer layer includes forming the trench through the protection layer.20. The method of claim 15, further comprising bonding a thermal die tothe thermally conductive feature.